Process for producing crimped filaments



United States Patent 3,443,002 PROCESS FOR PRODUCING CRIMPED FILAMENTSTaiichi Murao, Shigeo Katsuyama, and Toshio Sasaki, Nobeoka-shi. Japan,assignors to Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, Japan NoDrawing. Filed Oct. 26, 1966, SenNo. 589,488 Int. Cl. D02j 1/22; D01d5/08, 5/22 US. Cl. 264-168 6 Claims ABSTRACT OF THE DISCLOSURE A processfor producing a crimped filament in which there are melt conjugate-spun,first and second constituents, to form a composite filament, the firstconstituent consisting essentially of a polyamide selected from thegroup consisting of nylon 6, nylon 66 and nylon 610, and the secondconstituent consisting essentially of the same polyamide with 1 to 10%by weight of glycerin incorporated therein. The resulting filament iscooled and stretched and thereafter treated with water to develop crimpstherein.

This invention relates to a process for producing crimped compositefilaments comprising polyamides. More particularly, the inventionpertains to a method for preparing crimped composite filaments by theconjugate-spinning of a polyamide incorporated with glycerin and thesame polyamide containing no glycerin.

Conventional methods for the production of crimped filaments are roughlydivided into two groups; one is a method in which filaments aremechanically crimped and then the crimps are subjected to heat-setting,and the other is a method in which filaments are crimped by beingbrought into a bilateral structure. It is thought, however, that thelatter method gives more natural crimps. Particularly, in the case oflong filaments, crimps are developed, if necessary, after the filamentshave been formed into products such as fabrics or textures and thereforeit is considered that the latter method is effective for such.filaments. Such latently crimpable filaments (conjugatespun compositefilaments of the type developing no crimps unless they are subjected toheat-treatment in a nontensioned state after stretching, will bereferred to as latently crimpable filaments, hereinafter) are formed bysubjecting two kinds of polymers to conjugate-spinning. In this case,the two constituent polymers are required to be similar in chemicalstructure and crystal structure. If the two constituents are dilferentin chemical structure and crystal structure, there is brought about sucha drawback that the resulting composite filament may be separated. Itis, however, needless to say that no crimps are developed if the twoconstituents-are entirely the same polymers. For the above reasons, theconventional methods utilize two kinds of polymers, e.g., homopolymerssuch as nylon 6 and nylon 66 or nylon 610, or copolymers thereof. Thus,the conventional methods require the preparation of two kinds ofpolymers and hence are inconvenient to be practiced on a commercialscale. Moreover, the conventional methods suffer from the drawback thatthe time to develop crimps is difficulty controlled.

An object of the present invention is to provide a process for producinglatently crimpable composite filaments which can be practicedeconomically and can easily control the resulting crimps.

In accordance with the present invention, one component employed is apolymer mixture prepared by incorporating 1 to 10% of glycerin into astarting polymer, e.g. a polyamide such as nylon 6, nylon 66 or nylon610, and the other component is the same polymer as above in which noglycerin has been incorporated. Using a con- 3,443,002 Patented May 6,1969 lateral structure and the resulting filament is stretched.

The obtained filament is treated with water or hot water and theglycerin contained in the one of the constituents is dissolved out,whereby a structural difference between the two constituents is broughtabout to give crimps to the filament. In case the filament is furthersubjected to heat treatment, after the treatment with water or hot waterto dissolve out glycerin, the crimps of the filament become even better.It is considered that in the above case, the crimps are developed forthe reason that glycerin acts as a solvent for polyamides and, incooling and crystallizing, the polyamide containing glycerin is madedifferent in behavior from the polyamide containing no glycerin to forma bilateral structure which, when the glycerin is dissolved-out bytreatment with water or hot water, is further intensified to developcrimps. In this instance, in case the amount of glycerin added is morethan 10%, the effect of glycerin as a solvent becomes excessive wherebythe polyamide is lowered in viscosity and is deteriorated inspinnability to form no filament, in some cases. In case the amount ofglycerin is less than 1%, the crimp-developing elfect is lowered and thehomogeneous mixing of glycerin and polyamide becomes difiicult to lowerthe uniformity of the resulting crimps.

In accordance with the present invention, the starting polymer is onlyone kind of polymer, and therefore the invention is advantageous in thesupply of starting materials. Further, the invention gives the advantagethat since crimps are developed by treatment with hot water, no crimpsare substantially developed after the stretching of the filament, andcrimps can be easily developed, at any time whenever these are desiredto be formed, by hot water treatment preferably followed by heattreatment.

The invention will be illustrated further in detail with reference tothe following examples:

Example 1 In this example, one constituent employed was nylon 6 and theother constituent was prepared by incorporating 5% by weight of glycerininto nylon 6. Using a conjugatespinning machine provided with a knownside-by-side type spinneret, the above two constituents weremelt-extruded in a ratio of 1:1 at an extrusion temperature of 275 C.The resulting filament was cooled and was stretched to 4.0 times in airto obtain a latently crimpable filament having a tenacity of 4.2 g./d.and an elongation of 20%. This filament was treated with hot water at C.for 30 minutes to dissolve out glycerin and was then dried in air. Theobtained filament was an excellent crimped filament having 32 crimps perinch.

Example 2 In this example, one constituent employed was nylon 66 and theother constituent was prepared by incorporating 10% by weight ofglycerin into nylon 66. In the same manner as in Example 1, the abovetwo constituents were subjected to conjugate-spinning and the resultingfilament was stretched to obtain a latently crimpable filament having atenacity of 4 g./d. and an elongation of 22%. This filament was treatedwith water for one hour to dissolve out glycerin and was then dried inhot air at C. The obtained filament was an excellent crimped filamenthaving- 46 crimps per inch.

Example 3 In this example, one constituent is nylon 610 and the otherconstituent was prepared by incorporating 10% by weight of glycerin intonylon 610. In the same manner as in Example 1, the above twoconstituents were subjected to conjugate-spinning and the resultingfilament was stretched to obtain a latently crimpable filament having atenacity of 4.2 g./d. and an elongation of 20%. This filament wastreated with water for one hour and was then dried in air. The obtainedfilament was an excellent crimped filament having 21 crimps per inch.

What we claim is:

1. A process for producing a latently crimpable linear polyamide productwhich comprises melt conjugate-spinning first and second constituents toform a composite filament, the first constituent consisting essentiallyof a polyamide selected from the group consisting of nylon 6, nylon 66andnylon 610 and the second constituent consisting essentially of thesame polyamide with 1 to 10% by weight of glycerin, and then cooling andstretching the resulting composite filament.

2. A process according to claim 1 wherein the constituents are spun inside-by-side relation.

3. A process according to claim 1 wherein said constituents aremelt-spun at a temperature of about 275 C.

4. A process for producing a crimpecl filament which comprises meltconjugate-spinning first and second constituents to form a compositefilament, the first constituent consisting essentially of a polyamideselected from the group consisting of nylon 6, nylon 66 and nylon 610and the second constituent consisting essentially of the same polyamidewith 1 to 10% by weight of glycerin, cooling and stretching theresulting filament and then treating the filament with water to developcrimps therein.

5. A process according to claim 4 wherein the temperature of the waterin which said filament is treated is C.

6. A process according to claim 4 wherein the constituents are spun inside-by-side relation.

References Cited UNITED STATES PATENTS 2,439,815 4/1948 Sisson.

2,695,835 11/1954 Hare 264182 2,824,780 2/ 1958 Satterthwaite.

2,846,727 8/1958 Bechtold 26449 2,996,474 8/ 1961 Voigt.

3,182,100 5/1965 Bedell.

3,209,402 10/ 1965 Riley et a1.

3,235,634 2/1966 Michel.

3,276,996 10/1966 Lazare 106162 X 3,323,978 6/1967 Rasmussen 161l693,351,495 11/1967 Larsen et a1 136146 JULIUS FROME, Primary Examiner.

I. H. WOO, Assistant Examiner.

US. Cl. X.R. 26417l, 344

